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Add drawModel

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Miloslav Číž 2018-11-20 09:35:05 +01:00
parent 3a14f0de21
commit cc76683114
1 changed files with 93 additions and 6 deletions
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99
s3l.h
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@ -7,6 +7,38 @@
author: Miloslav Ciz
license: CC0 1.0
--------------------
COORDINATE SYSTEMS:
In 3D space, a left-handed coord. system is used. One spatial unit is split
into S3L_FRACTIONS_PER_UNIT fractions.
y ^
| _
| /| z
| /
| /
[0,0,0]-------> x
Untransformed camera is placed at [0,0,0], looking forward along +z axis. The
projection plane is centered at [0,0,0], stretrinch from
-S3L_FRACTIONS_PER_UNIT to S3L_FRACTIONS_PER_UNIT horizontally (x),
vertical size (y) depends on the camera aspect ratio. Camera FOV is defined
by focal length.
y ^
| _
| /| z
____|_/__
| |/ |
-----[0,0,0]-|-----> x
|____|____|
|
|
Coordinates of pixels on screen start typically at the top left.
*/
#ifndef S3L_H
@ -25,18 +57,19 @@ typedef int16_t S3L_Unit; /**< Units of measurement in 3D space. There is
#define S3L_FRACTIONS_PER_UNIT 1024
typedef int16_t S3L_ScreenCoord;
typedef uint16_t S3L_Index;
typedef struct
{
S3L_Unit x;
S3L_Unit y;
S3L_Unit z;
} S3L_Vec3;
uint16_t resolutionX;
uint16_t resolutionY;
S3L_Unit focalLength; ///< Defines the field of view (FOV).
} S3L_Camera;
typedef struct
{
S3L_ScreenCoord x; ///< Screen X coordinate.
S3L_ScreenCoord y; ///< Screen Y coordinate.
S3L_ScreenCoord x; ///< Screen X coordinate.
S3L_ScreenCoord y; ///< Screen Y coordinate.
S3L_Unit barycentric0; /**< Barycentric coord 0 (corresponds to 1st vertex).
Together with 1 and 2 coords these serve to
@ -46,6 +79,7 @@ typedef struct
S3L_FRACTIONS_PER_UNIT. */
S3L_Unit barycentric1; ///< Baryc. coord 1 (corresponds to 2nd vertex).
S3L_Unit barycentric2; ///< Baryc. coord 2 (corresponds to 3rd vertex).
S3L_Index triangleID;
} S3L_PixelInfo;
#define S3L_BACKFACE_CULLING_NONE 0
@ -477,4 +511,57 @@ void S3L_drawTriangle(
#undef stepSide
}
void S3L_mapViewToScreen(
S3L_Unit viewX,
S3L_Unit viewY,
S3L_Unit viewZ,
uint16_t screenWidth,
uint16_t screenHeight,
S3L_ScreenCoord *screenX,
S3L_ScreenCoord *screenY)
{
uint16_t halfW = screenWidth >> 1; // TODO: precompute earlier?
uint16_t halfH = screenHeight >> 1;
*screenX = halfW + (viewX * halfW) / S3L_FRACTIONS_PER_UNIT;
*screenY = halfH - (viewY * halfW) / S3L_FRACTIONS_PER_UNIT;
}
void S3L_drawModel(
const S3L_Unit coords[],
const S3L_Index triangleVertexIndices[],
uint16_t triangleCount,
S3L_Camera camera,
S3L_DrawConfig config)
{
S3L_Index triangleIndex = 0;
S3L_Index coordIndex = 0;
while (triangleIndex < triangleCount)
{
S3L_ScreenCoord sX0, sY0, sX1, sY1, sX2, sY2;
S3L_Unit vX, vY, vZ;
S3L_Unit indexIndex;
#define mapCoords(n)\
indexIndex = triangleVertexIndices[coordIndex] * 3;\
vX = coords[indexIndex];\
++indexIndex; /* TODO: put into square brackets? */\
vY = coords[indexIndex];\
++indexIndex;\
vZ = coords[indexIndex];\
++coordIndex;\
S3L_mapViewToScreen(\
vX,vY,vZ,camera.resolutionX,camera.resolutionY,&sX##n,&sY##n);
mapCoords(0)
mapCoords(1)
mapCoords(2)
S3L_drawTriangle(sX0,sY0,sX1,sY1,sX2,sY2,config);
++triangleIndex;
}
}
#endif